Here's the 6.1 Hemi Jonathan LaPaglia swapped into his '73 Challenger. He performed this s
First off, here's the good news: The block drops right into place. Yes, with a simple pair of adapter plates bolted to the block, a new Hemi engine will go into any old Mopar muscle car. However, the problems start piling up when you begin to add stuff to the block--you know, essential things like an oil pan, headers, a cooling system, wiring, and a transmission. OK, this swap really isn't easy, but Mopar guys are always up for the challenge (pun intended). Anyone with a Summit catalog and a telephone can build a Chevy, and the Ford guys have it pretty easy, too. But die-hard fans of Ma Mopar are more like pioneers of the Wild West. They need to do more of their own engineering because there simply isn't the volume of parts available for their cars. Now, say you want to do something crazy like swap a new engine into your old Dodge or Plymouth, and you're really asking for trouble.
The new Hemi, referred to as the Gen III, has been around since 2003, and as more engines become available at lower prices, more guys are considering this swap. As more people do the swap, more parts become available to make the job easier--and the business of new Hemi swaps is literally exploding. We spoke with several companies that are making parts needed to adapt the newer engines to A- B- and E-Body Mopars with a minimal amount of frustration. Mopar freaks, pay attention. We'll give you the rundown.
The new Hemi first appeared in the '03 Dodge 2500 and 3500 fullsize pickups as a replacement for the Magnum 5.9 (360-cid) engine. It displaced 5.7 liters, and even though the figure should be closer to 350 ci, Chrysler literature often lists displacement as 345 cid, for marketing purposes we're guessing, because the horsepower rating is 345 also. Coincidentally, those figures (345/345) are the same as the '57 DeSoto Adventurer, the first domestic mass-produced engine to make 1 hp per cubic inch as the standard (nonoptional) engine.
If you want to keep your old automatic trans, you'll need an adapter kit to line up everyt
In 2004, the 5.7 was an option for the midsize Durango pickup and made its first appearance in passenger cars with the '05 Chrysler 300C. In the '05 model year, a bigger-bore 6.1 (372-cid) version was launched in the SRT8 versions of the 300C and Jeep Grand Cherokee and was subsequently rolled out into Chrysler's other models as more SRT8 versions were developed.
To Swap Or Not To Swap?
The new Hemi is a cool engine that is better than previous Chrysler V-8s in nearly every way. It weighs less, is manufactured to tighter tolerances, is more fuel efficient, and has greater output per cubic inch. In fact, the 6.1 Hemi has the highest power-per-cube rating of any Chrysler engine to date. Knowing that, who wouldn't want one of these in his car? Of course, the resto and Concours guys won't, but the dude looking for reliable, tunable, modern performance wrapped in classic sheetmetal will find this option irresistible. JR Bouchillon of Bouchillon performance says he's sold more new Hemi engines than any other engine his company offers. And his is a family-owned, Mopar-specific business with a 40-year history.
So is the new Hemi right for your project? Old-school guys will say no, and we can appreciate that. The new engines lack the fist-to-the-gut impact of a Six Pack 440 or 426 Elephant Hemi. Plus, the new Hemi swap is by no means a drop-in, weekend job, so you're looking at hours (or years) of work or big bucks to send your car to a shop. Even if you do the job yourself, it won't be cheap. Among other things, you'll need a number of custom parts, new adapters and fittings, a revamped fuel system, and all the electronics to run the engine. If you are down with all that, the trade-off will be "a 425hp engine that gets 22 mpg that you can drive every day," according to Jonathan LaPaglia, who was one of the early adopters of the swap, dropping a 6.1 into his '73 Challenger. He speaks with authority, too. He did the swap himself, and he drives his Challenger every day.
Bouchillon makes a kit to connect a 727/904 kick-down cable. The company has just develope
Take The Plunge
Once you start down this path, there are a number of pitfalls waiting to trip you up. Most of them are clearance issues of the sort you'd expect to encounter when trying to fit two things together that were never designed for each other. To keep the number of variables down, we are assuming that if you are contemplating a new Hemi swap, you plan to keep the fuel-injection system intact. Carbureted intake manifolds are available, and some companies are making a distributor to replace the individual ignition coils, however, we don't see the logic in performing this swap and tossing the EFI stuff. If you want a carburetor, build a traditional Mopar V-8 instead.
The first aspect you need to decide is if you are going to keep the factory K-frame or go with an aftermarket one. The K-frame, or K-member, is a piece of stamped steel that bolts in and ties together the front of the unibody. It also serves as the engine crossmember. As you can guess, it's shaped like the letter K, and aftermarket versions are available from several companies such as XV Motorsports, RMS Chassis Components, and Magnum Force Race Car Fabrication. Everything you do to perform this swap will be based on which K-frame you're using because it's what locates the engine in the chassis. That affects what oil pan, exhaust, transmission crossmember, and accessory drive you'll need. Obviously, it is much less expensive to use the stock K-frame, but if you have access to any government bailout money, an aftermarket K offers much more clearance because it gets rid of the shock towers and torsion bars, replacing them with upper and lower control arms and coilover shocks.
TTI makes a motor mount that will let you drop a new Hemi into any classic Mopar.
Your next decision will be to choose a transmission. If your car is an automatic, do you want to keep your 727/904? On the new Hemi, the crank flange sticks out of the engine block a little farther than any of the previous small and big V-8s, so you'll need a special adapter and flexplate. You'll also need a starter with an extended reach to make up for the additional distance. Be sure your transmission is for a small-block, too. The big-block transmissions won't fit the new Hemi.
You'll also need to attach the 727's kick-down cable, which can be a big problem, considering the new Hemi engines all have electronic throttle bodies (see the Drive By Wire section). Bouchillon solves this problem with its newly developed kick-down cable kit that will work with the factory throttle body or an aftermarket cable-actuated throttle.
If you want an overdrive automatic, there are a couple of choices. Chrys-ler's 545RFE five-speed automatic will fit under most Mopar muscle car floorpans with a little clearancing of the floor with a hammer. You'll need to make a transmission crossmember to fit the new trans mount location, too. But the advantage of using this transmission is it can be controlled by the factory ECM. You won't need to buy a separate transmission control unit. The other option is to use a kit from Keisler that mates a GM (gasp) 4L60E with a Mopar bellhousing.
TTI was among the first to make swap headers that fit the new Hemi.
If you want a manual transmission, things are a little trickier. Keisler sells a kit that includes either a TKO500 or 600 and all the pedals and linkage you'll need. There will be clearance problems with this gearbox, though, and you may need to cut and reshape sections of the floor to make it fit. So far, we haven't heard of anyone adapting an old-school A833 four-speed to fit. Write us with the details if you have.
You can easily fit a new block to an older chassis with adapter plates available from several aftermarket companies. Be sure to go with the same company you will be buying your headers from. TTI sells both biscuit and spool-type mounts to cover all Mopars from '62 to '76. Street & Performance makes engine plates that adapt the new block's bolt pattern to fit 440-style frame mounts. Source your headers from S&P, too, if you go this route.
It cannot be stressed enough--buy the headers that match your motor mounts. TTI has this market covered and offers headers to fit the factory or an aftermarket K-frame and will clear either a 727 trans or a Keisler-supplied manual. If money or clearance is really tight, you can probably use the stock manifolds. On its website, Street & Performance details an install of a 5.7 Hemi into a '70 Challenger. S&P decided to retain the factory manifolds so the owner could keep the stock power steering system.
From the factory, the 5.7 and 6.1 engines in passenger cars have front-sump pans. The truck applications are rear sump. But none of the factory pans will clear any stock K-frame and steering linkage in any classic Mopar. Bottom line--you'll need a custom pan. Milodon makes a midsump pan that will clear the factory K-frame and drag link. Bouchillon Performance makes several pans to fit the stock stuff as well as aftermarket K-frames and rack-and-pinion steering, and Charlie's Oil Pans will make you a pan in any configuration you want. Of course, you'll need to buy an oil pickup tube and dipstick to match the new pan.
Oil filter fitment is also a problem. Most new Hemi engines mount the filter to a boss on the passenger-side front of the block that would interfere with the factory K-frame. Many people recommend installing a block-off plate on the engine and running a remote-mount oil filter. LaPaglia discovered that the Dodge Durango uses an adapter that mounts its oil filter at a 45-degree angle to the block, and that gave him just enough clearance to mount a filter to the block using factory parts. Beware, though, that the oil filter itself is too big. You can unscrew it from the adapter, but it will hit the K-frame before you can pull it out, and you'll have to jack up the engine to remove it. LaPaglia discovered that a Fram PH3512 filter fits the boss and is short enough to fit without breaking out the engine hoist every time you change the oil.
On LaPaglia's car, there is little room between the bottom of the engine block and the fac
The new Hemi water pump has coolant in the inlet and outlet fittings on the passenger side of the block. You, therefore, need a radiator with matching fittings on the passenger side. LaPaglia found a Ron Davis radiator that fit his Challenger and the new water pump. You'll also need to spend some time finding properly bent radiator and heater hoses. Be sure to budget for a good pair of fans, too. The 6.1 engines have no provisions for mounting a mechanical fan, so you have to use electric fans. Some of the 5.7 engines, mostly from fullsize pickups, can use a mechanical fan, though. LaPaglia uses a pair of Spal fans to keep coolant temperatures in check. Bouchillon sells a complete radiator and fan kit for any classic Mopar.
As equipped from the factory, the new Hemi is a returnless system--high-pressure fuel is pumped to the engine by a pulse-width-modulated fuel pump, but there is no return line back to the tank. Though you can run an external fuel pump, an in-tank pump makes for a cleaner install. Street & Performance sells a return-type regulator and fuel filter assembly that mounts close to the tank, and you can alter your stock tank with a fitting to accept the return line. The advantage to this is you don't need to alter or replace the factory fuel rail to accept a regulator and return line fitting and plumb a return fuel line. Bouchillon Performance sells a similar kit that uses an in-line pump and a fuel filter that doubles as a pressure regulator.
The Durango angled oil filter adapter keeps you from having to plumb in a remote oil filte
LaPaglia recommends replacing your car's original gas tank with a baffled tank specifically designed for fuel injection. He did not and therefore has fuel starvation issues in hard cornering situations when his tank is less than half full. Unbaffled, fuel slosh in the tank can uncover the fuel pickup.
Your old accessories won't fit the new engine, so you'll need the new engine's alternator, water pump, power steering pump, and A/C compressor if you want air conditioning. All the engine-driven accessories mount to the front timing cover, and the new Hemis have two different covers: one for the trucks and one for the passenger cars. In most applications, the passenger-car timing cover is the better choice.
It is possible to keep or even add air conditioning when swapping in a new Hemi, but you'll have to use the new engine's compressor. That compressor will fit your engine compartment, but you may need to notch the K-frame for clearance. You will also need to dimple the No. 1 cylinder's header tube and grind a mounting tab off the back of the compressor. LaPaglia wrapped his lines with heat-resistant insulation--the headers can't get any closer than this. Also, the new compressor's fittings are different from the threads on the older car's lines. You'll need adapters to fit the old lines to the new compressor.
Use a shorter-than-stock filter if you want to be able to remove it easily.
The new Hemi cooling system is radically different from A, B, RB, and 426 Hemi engines.
You can mount an A/ C compressor, but it is a really tight fit.
LaPaglia was able to keep his Challenger's stock power steering box. Dart, Duster, and Val
B- and E-Body Mopars can also keep the factory power steering gearbox, but it's a really tight fit, too. A-Body owners aren't so lucky. There simply isn't room for the power steering box, and you'll likely need to convert to the smaller manual steering box. The new Chrysler pump operates at around 1,600 psi--too high for the older car's components, according to most people we talked to. They warned of blown seals and chronic leaks. The solution most recommended was to replace the Chrysler pump with a GM because they operate at lower pressures, about 1,100 psi. However, for the guys who just can't bring themselves to put any GM part on a Mopar, Bouchillon offers a reduced-pressure Chrysler. He says they're such a popular item, he can't keep them on the shelves.
To control your new engine, there are three different options: two stand-alone systems and one that uses a factory ECM. The simplest option is to use the factory ECM. A stock Chrysler ECM can be reflashed to run the new engine in the older car and ignore certain sensors and operations like EGR solenoids and fuel tank pressure sensors. A limitation with a factory ECM is it will need to be reprogrammed if you decide to change things like cams and cylinder heads or add boost or nitrous oxide at a later date. These things would increase airflow through the engine past the limits the base ECM programming can compensate for. Obviously, this would only be an issue if you plan on adding more power down the road.
The Bouchillon low-pressure Mopar power steering pump kit is in this photo.
A better option for guys who are always tinkering is a stand-alone engine management system, and there are two big players you can choose from. FAST and Mopar Performance make systems that are fully programmable via a laptop computer and the accompanying software. Of the two, the Mopar Performance system is a little easier to use. It comes loaded with a basic program that will allow you to start the car and drive it around on a very basic tune. The FAST XFI computer comes with no base program, so you'll have to dial in a basic program yourself. It does offer a dizzying array of parameters to fiddle with, though, and would be perfect for the nerdy, electronics types. No matter which system you choose, your engine will run best when tuned on a chassis dyno, so find a shop you can work with.
There are several options available to run the new engine. LaPaglia uses a Mopar Performan
Drive By Wire
All new Hemis come with an electronic throttle body, or drive by wire. This poses a problem because you need to use a matching electronic accelerator pedal, and we can guarantee the new one will look odd and out of place in your older car. Mopar Performance makes a traditional cable-operated throttle body that includes a throttle-position sensor to communicate with the ECM. You'll need to come up with a properly routed bracket, however. Another option is to use what's known as the black box. Fullsize pickups use a cable-style gas pedal, and that cable is connected to a box under the hood that converts the input to a digital signal that then operates the electronic throttle. This cable-operated box can be adapted to your old car's throttle cable, and you can keep the engine's electronic throttle body.
LaPaglia recommends making some sort of cold air intake ducting rather than using a conical air filter clamped to the throttle body. He tells us he was seeing intake air temperatures of more than 180 degrees before he installed his. At intake temperatures that high, engine performance is greatly diminished because the computer retards timing to prevent detonation. He made a great-looking airbox out of ABS plastic, routing the inlet just behind the lower grille opening.
Yes, this is a complicated job. But the good news is there are more people doing it than ever before. That means there are more sources for information and more aftermarket engineering and support, so it's likely you'll be able to find a solution to any problem you encounter while doing the swap. If you like a challenge, this is the swap for you. The new Hemis are great engines with a ton of potential.
See the May '08 issue of CC for a feature on Jonathan's car.
Also shown is a reprogrammed Chrysler ECM.
This is the Mopar Performance throttle body that replaces the new Hemi's drive-by-wire thr
This is the airbox assembly LaPaglia made to keep his air inlet temperatures down.
If you buy any parts from Bouchillon Performance, be sure to mention this article. JR Bouc
|HEMI SPECS |
| ||5.7 ||6.1 |
|Bore ||3.92 ||4.10 |
|Stroke ||3.58 ||3.58 |
|Deck height ||9.3 ||9.3 |
|Compression ratio ||9.6:1 ||10.3:1 |
|Combustion chamber ||84.5 cc ||71.5 cc |
|Intake valve ||2.00 ||2.05 |
|Exhaust valve ||1.55 ||1.55 |
|Horsepower ||345 ||425 |
|Torque ||375 ||420 |
All measurements are in inches.Power levels vary slightly from model and increased with each model year--the 5.7 in the '09 Challenger makes 375 hp.
Similarities And Differences Between The 5.7 And 6.1
Both engines share a number of features, including the following:
Cast-iron, deep-skirt block with cross-bolted main caps
Aluminum cylinder heads
Dual plugs--two spark plugs per cylinder
Drive by wire (electronic throttle body)
Externally, the blocks are the same size, however, they are different enough on the inside that they cannot interchange; 6.1 Hemis have the following revisions:
Additional block reinforcement
Bigger bore, 4.10 inches versus 3.92 inches
Revised coolant passages
Oil squirters to cool the bottoms of the pistons
Billet steel camshaft
Hollow intake valves, sodium-filled exhaust valves
Revised oil pan to reduce windage
Larger intake and exhaust ports
Cast-aluminum intake manifold (instead of molded plastic)
No MDS (multidisplacement system)
|WHICH PLATFORM? |
|LX ||300C, Magnum R/T, Charger R/T, and SRT8 models |
|LC ||Challenger R/T and SRT8 |
|WK ||Grand Cherokee and Grand Cherokee SRT8 |
|DR ||Fullsize pickup |
|Bouchillon Performance Engineering||Magnumforce Race Car Fabrication|
|Hanahan, SC||Campbell, CA|
| || |
|Charlie's Oil Pans||RMS Chassis Components|
|Norton, OH||White Haven, PA|
| || |
|Fuel Air Spark Technology||Street & Performance|
|Memphis, TN||Mena, AR|
| || |
|Inertia Motorsports||TTI Performance Exhaust and Headers|
|Austin, TX||Corona, CA|
| || |
|Keisler Engineering||XV Motorsports|
|Rockford, TN||Irvington, NY|